Profile prediction of negative triangularity plasma in ASDEX Upgrade using PORTALS-GX

The PORTALS framework [1] couples local gyrokinetic simulations (CGYRO [2], TGLF [3, 4]) with global transport solvers (TRANSP [5]), and leverages surrogate modelling and optimization techniques to iteratively solve for steady-state, flux-matched plasma profiles. This framework produces high-fidelity predictions of core plasma profiles and performance at significantly reduced costs, with no loss of accuracy. In this work, the nonlinear gyrokinetic code, GX [6], was first benchmarked against CGYRO for a negative triangularity case from ASDEX Upgrade [7], accounting for Miller geometry, electromagnetic effects, 3 gyrokinetic species, and ITG and TEM turbulence drive. We found that GX models ITG turbulence well, but underestimates TEM turbulence. GX was then coupled with PORTALS and the first tokamak profile prediction using this code was performed. The results were compared to previous PORTALS-CGYRO [8] and ASTRA-TGLF [9] studies and validated against experimental measurements. With GX capable of accepting either 2D or 3D plasma shaping, the new PORTALS-GX framework expands the scope of profile prediction to both tokamak and stellarator geometries, which future work aims to explore.